1. Field of the Invention
Embodiments of the present invention generally relate to using depth information to create and monitor three-dimensional (3D) tripwires in video.
2. Description of the Related Art
One of the popular functions of camera-based (video analytics) automatic surveillance systems is to detect/alert when objects cross over a user-defined virtual line in the scene under surveillance. Typically, this “line” (commonly referred to as a video tripwire or video trip zone) is defined using a point-and-click graphical user interface which is overlaid on a two-dimensional (2D) video frame. The line may be specified explicitly by its two end-points, or as the adjacent edge of two polygons. An underlying video analytics algorithm then compares the 2D (x,y) coordinates of detected objects against the 2D line, and generates an alarm if an object crosses or intersects that line. Because these 2D coordinates are merely projections of a 3D (x,y,z) world onto the 2D image plane, there is inherent ambiguity in the desired alert behavior, resulting in potential false alarms.